Yea, I’m reading about Mithraism and its possible survivals right now, this leads me to the Grail Cycle and to Rahn.

Stoyanov is the best source on the dualist heresies and religions, I don’t think anyone else has come close to doing that, before Stoyanov it was undemonstrated that the Cathars were Bogomils who introduced Zurvanist-Tengrist ideas into Europe.